In conventional water-cooled internal combustion engines, the fan for circulating air through the radiator is driven by a shaft which is located behind the radiator and which usually attaches to the water pump drive shaft. The shaft itself may be driven by a belt that engages a sheave or a pulley disposed about the shaft. The fan must be located in very close proximity to the radiator in order to provide sufficient air flow through the radiator to provide the necessary cooling effect.
To this end, current fan shafts, identified generally as 20 in FIG. 1, typically mount to the water pump using four long bolts 22 that extend into the water pump assembly. The fan 25 is attached to the hub end 24 of the shaft 20 using four shorter bolts 26. When removing the fan 25, each of the four shorter bolts 26 must be removed and there is usually not much room to work between the radiator and the fan 25. Thus, removal of the fan 25 is a difficult and often time consuming task. Additionally, if the engine has been recently operated, the radiator can be extremely hot creating a serious bum risk to the person faced with the unpleasant task of removing the fan 25.
For ordinary vehicles, the inability to quickly and easily remove the fan blades from the shaft is of little consequence. However, in the automobile racing industry it is well known that if the fan blades are removed, the engine can produce as much as fifteen percent more horsepower. Such a significant horsepower increase is, of course, a very desirable effect. The problem with removing the fan blades is that they can only be removed for very short periods of running the engine or there is a dangerous probability of the engine overheating with severe damage resulting therefrom. Thus, it has become a common practice in the racing industry to remove the fan blades from the racing vehicle during time trials and to replace the fan blades for the full race.
Accordingly, there is a need for a fan spacing shaft from which the fan blades can be quickly and safely removed. Further, it would be desirable if such a fan spacing shaft were economical and could function as well as traditional fan spacing shafts.